Hello, Thanks for the query.
Niacin 500 mg does cause a number of side effects particularly when therapy is initiated. The symptoms noticed are headache,
dizziness,
flushing (warmth, redness, or tingly feeling under your skin), itching,
dry skin,sweating, chills,
muscle pain,
leg cramps, sleep problems insomnia),
blurred vision, nausea, vomiting, diarrhea, belching, gas. Therefore, it is better to take the drug at night tme to reduce the intensity of these side effects. These effects reduce over a period as the drug is better tolerated. Thanks.